scripts/cross-build-mingw.sh: Allow to specify the build directory

This can be useful to maintain 2 separate build directories in parallel,
i.e. for GTK2 and 3 builds.

scripts/cross-build-mingw.sh

@@ -22,17 +22,19 @@ GTK3=no
 CONFIGUREFLAGS="--enable-nls"
 MAKEFLAGS="${MAKEFLAGS:--j2}"
 
-while getopts '32h' o; do
+while getopts '32b:h' o; do
   case "$o" in
     3) GTK3=yes;;
     2) GTK3=no;;
+    b) BUILDDIR="$OPTARG";;
     h)
       cat <<EOF
-USAGE: $0 [-2|-3] [-h]
+USAGE: $0 [-2|-3] [-b DIR] [-h]
 
--2  Build against GTK2
--3  Build against GTK3
--h  Show this help and exit
+-2      Build against GTK2
+-3      Build against GTK3
+-b DIR  Use DIR as build directory
+-h      Show this help and exit
 EOF
       exit 0;;
     *) echo "Invalid option $o (see -h)">&2; exit 1;;